This invention relates generally to portable respiratory protection devices and more particularly to positive-pressure respiratory protection devices which include at least one detachable filter mounted on a housing and a blower located in the housing to draw ambient air into the housing through a suction opening which is supplied under pressure to the filter.
Devices of this type are required by persons who require respiratory assistance in order to overcome inhalation resistance. Such devices are also part of the equipment utilized by pilots and persons who must work in contaminated environments. The power supply for the blower is usually a battery pack which is located within the housing. The blower draws ambient air into the housing through a suction opening and forces the air under pressure through the filter. These devices are generally called positive-pressure respiratory protection devices and are more reliable than devices in which the air is drawn through the filter by a low pressure. In addition, the devices of the invention are simply constructed so that the air volume can be controlled, i.e., the amount of air which is delivered to the filter by the blower can be adjusted to the requirements of the user.
Presently known devices of this type are unwieldy and bulky and require a water drip or spray into the housing which can damage the blower, the blower controls and the battery pack.
The invention provides a portable respiratory protection device, in which the suction opening in the housing shell is effectively protected against water drip or spray and which is compact and easily manageable. The device is relatively inexpensive to manufacture and is simple to operate and maintain.
In a device according to the invention the suction opening in the housing shell is closely adjacent to a portion of the exterior of the filter and ambient air is drawn from spaces between the housing and the filter through the suction opening when the blower is operating. The suction opening is essentially covered by the adjacent portion of the filter and is thereby protected against the entrance of water drip or spray and other liquids and solid materials in the ambient air. Because a portion of the filter serves as the cover for the suction opening, no additional protection such as louvers or a screen is required.
According to the invention, the housing includes at least one arm which supports a filter. An air channel formed in the arm leads from the blower located in the housing body to a connecting opening located in the housing arm which is in communication with the filter inlet. This arrangement results in a compact construction and a short air channel between the blower and the filter.
The features which characterize the invention are pointed out with particularity in the claims annexed to and forming a part of this disclosure. For a better understanding of the invention, its operating advantages and the specific objects attained by its use, reference should be had to the accompanying drawings and descriptive matter in which preferred embodiments of the invention are illustrated and described. Like reference characters describe like parts throughout the drawings.